Usually, in the manufacturing process of semiconductor devices, there is a processing step in which the resist is deposited as a photomask for exposure on Si or another semiconductor substrate. In this processing step, for example, in the case of an 8-in Si wafer, the resist material is deposited as shown in FIGS. 5 and 6.
As shown in graph a in FIG. 5, first the semiconductor substrate 102 is rotated at a constant velocity of 1500 rpm. As shown in graph b, about 1 sec after the start of rotation, feeding of resist material 103 to the central portion of semiconductor substrate 102 is initiated (FIG. 6(a).
As resist material 103 is fed while semiconductor substrate 102 is rotated at the velocity for about 4 sec, resist material 103 spreads toward the circumferential portion of semiconductor substrate 102 as shown in FIGS. 6(b)-(d).
Then, as the supply of resist material 103 is stopped, the rotational velocity of semiconductor substrate 102 is raised to 3500 rpm, and the resist film is deposited.
By using this method, it is possible to form a resist film with a nearly uniform film thickness on semiconductor substrate 102.
However, in the conventional deposition method, in order to deposit resist material 103 over the entire surface of semiconductor substrate 102 without any unevenness, a significant amount of resist material 103 is required. As a result, the manufacturing cost of the semiconductor devices increases.
On the other hand, if the amount of resist material 103 supplied is reduced in the aforementioned conventional method, the resist material may be applied unevenly, making reliable deposition impossible. This is a disadvantage.
The purpose of the present invention is to solve the aforementioned problems of the conventional methods by providing a resist material deposition method which enables reliable deposition with a small amount of resist material, free of unevenness.